| 摘要 |
A zoom lens system has (in order from the object side of the lens system) a first lens unit with a positive refractive power, a second lens unit with a positive refractive power, and a third lens unit with a negative refractive power. The second lens unit has (in order from the object side of the lens system) an aperture stop, a negative lens element, a positive lens element, and a cemented doublet. Airspaces are disposed between the first and second lens units, between the third lens element and the cemented doublet, and between the second and third lens units. The lens system performs a zoom operation when the lens units are moved toward the object side so that the airspace between the first and second lens units is widened while the airspace between the second and third lens units is narrowed.
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